Ash's acoustic rabbit hole

[ADFinlayson]

I've done some tinkering and there is still a little buzz but I think there are still a few variables that are causing it - I think I've got the action set way lower than normal for a steel string, it only has 10 gauge strings on, I haven't glued the fretboard yet and the biggest factor is potentially my playing style as this is the first steel string I've owned - I fret on or close to the fret a lot of the time but fretting in the middle of the gap between the frets seems not to buzz

Anyway, here's a demo!

 

[mistermikev]

sounds pretty good.  lot of bass.  some nice playing too.  look at you and your right hand style.  nice work.

[Andyjr1515]

That sounds lovely!  (Nice playing too, although don't tell Ash - it will go to his head!)

Great balance and nice bass reponse - particularly impressive for the style of acoustic!  I reckon you got your top thickness and bracing carves just about spot on

 

[ADFinlayson]

On 8/20/2022 at 2:44 PM, Andyjr1515 said:

That sounds lovely!  (Nice playing too, although don't tell Ash - it will go to his head!)

Great balance and nice bass reponse - particularly impressive for the style of acoustic!  I reckon you got your top thickness and bracing carves just about spot on

 

Thanks Andy, yes I was impressed with the amount of bass, I was surprised because all the research said mahogany braces are a no no. The top is quite thin so is the back so I've only got 10 gauge strings on it which will probably be affecting tone. I was pleased to know that the amount of lacquer I would normally spray on an electric hasn't hampered the sound either. 

On 8/20/2022 at 1:17 PM, mistermikev said:

sounds pretty good.  lot of bass.  some nice playing too.  look at you and your right hand style.  nice work.

Thanks Mike, re picking, I do a lot of hybrid picking when I play guitar but as I've been playing this acoustic over the last few days I've noticed holding a pick is tying up my index finger so I've just got myself a couple of thumb picks, but wow those things are weird, way bigger and thicker than my usual 1mm black Dunlops so will def take a bit of getting used too, I'm tempted to try filing/thinning them down a bit. 

[mistermikev]

2 hours ago, ADFinlayson said:

Thanks Andy, yes I was impressed with the amount of bass, I was surprised because all the research said mahogany braces are a no no. The top is quite thin so is the back so I've only got 10 gauge strings on it which will probably be affecting tone. I was pleased to know that the amount of lacquer I would normally spray on an electric hasn't hampered the sound either. 

Thanks Mike, re picking, I do a lot of hybrid picking when I play guitar but as I've been playing this acoustic over the last few days I've noticed holding a pick is tying up my index finger so I've just got myself a couple of thumb picks, but wow those things are weird, way bigger and thicker than my usual 1mm black Dunlops so will def take a bit of getting used too, I'm tempted to try filing/thinning them down a bit. 

I never could make thumb picks work for me... have had some for years but I can't get used to how far away from the thumb the picking action is.  I spose I could cut one down... but just using fingers feels natural to me at this point.  I had no idea you were into that sort of thing - good for you. 

afa picks... I prefer stubby which is super thick... altho if playing acoustic I like the dava picks because they are thick and if you hold them at the tip they are rigid but if you hold them at the base they are good for strumming.  it's all good.  picks are such a personal choice thing.

[RVA]

Lovely tone and impressive build. Very nice playing also. Play it with joy and pride

[ADFinlayson]

26 minutes ago, mistermikev said:

I never could make thumb picks work for me... have had some for years but I can't get used to how far away from the thumb the picking action is.  I spose I could cut one down... but just using fingers feels natural to me at this point.  I had no idea you were into that sort of thing - good for you. 

afa picks... I prefer stubby which is super thick... altho if playing acoustic I like the dava picks because they are thick and if you hold them at the tip they are rigid but if you hold them at the base they are good for strumming.  it's all good.  picks are such a personal choice thing.

how far from the thumb the picking action is... exactly that. 

Thanks man, I am absolutely not a steel string acoustic player, I've never owned one but enjoying playing it. I took classical lessons as a kid which is where the finger picking comes from but I've pretty much solely played metal in drop C for 20 years 

[Prostheta]

8 hours ago, ADFinlayson said:

....I was impressed with the amount of bass, I was surprised because all the research said mahogany braces are a no no. The top is quite thin so is the back so I've only got 10 gauge strings on it which will probably be affecting tone....

My understanding is that this is a no-no also, but without knowing a specific rationale ("it's always been done this way!") it's absolutely something that should be subject to experimentation. Being not entirely sure as to why Spruce is the go-to, my first principles guessing would be any material's favourable properties for specific behaviours; stiffness-to-weight ratio, Young's modulus, whether sound propagates through a top made as a composite of dissimilar soft and hard woods differently, whether there's a difference in how the strings set the top into motion, whether a wood that produces bracing of a larger cross-sectional area is more amenable to finer tuning and shaving, etc. Not my area really, but a problem that is surely a rabbit hole. For me this moves very swiftly into the realms of speculation and hence the first level of Dante's rabbit hole.

We do have the benefit as individual builders of not having to factor excessive safety margins into builds as with more manufacturing-based building. We can tune every top individually and shave bracing to taste on a relaxed schedule rather than have a one size fits all brace sizing/shaping conveyor. It may simply be that Spruce is easy and forgiving, and other woods less so, yet suitable "in the zone". I'd like to think that this is the case.

edit: another property I was thinking about was the difference in seasonal expansion/contraction between differing materials.

[Bizman62]

My theory why spruce is so commonly used in braces and acoustic tops is that slowly grown quarter sawn spruce is very stiff especially against the cut edges of the growth rings. The winter rings are very hard and in good tight grained wood they're very near each other. It's like natural plywood or laminated paper, very uniform and predictable.

[Andyjr1515]

8 hours ago, Prostheta said:

My understanding is that this is a no-no also, but without knowing a specific rationale ("it's always been done this way!") it's absolutely something that should be subject to experimentation.

Yes - very much this.

However, even with only one variable - the brace shaving - I have come to the conclusion that the only way to know how far to go when shaving off wood from the braces when tap tuning is to make a number of guitars (and each would need to be made to completion) and each one shaving more and more mass off the braces until you go too far...and then just edge it back a bit.  Trouble is, for most of us that would take most of us a lifetime and fortune...  And then your offspring could maybe try the same thing with a different bracing pattern 

Like a lot of stuff, someone many decades ago stumbled across a combination of brace arrangement, size, timber and likewise top thickness and material that happened to work well and it became a lot easier to just use the same materials and design  than try all the permutations and combinations for something that works better.  Even Taylor took over 40 years to venture into a variation away from Martin's mid-1800's 'X brace'...

 

[Prostheta]

The weight of tradition and end-user expectation makes the introduction of something different a lot harder. Taylor had an uphill battle, but at least they had the reputation to back them up. The evolution of instruments can stagnate, sometimes for reasons of perfecting certain points and sometimes just stalling. Testing and picking apart the history to identify whether something is "because that's how it should be" or validating a reasoning is a vital exercise. Evolve or die!

[Nicco]

12 hours ago, Andyjr1515 said:

Yes - very much this.

However, even with only one variable - the brace shaving - I have come to the conclusion that the only way to know how far to go when shaving off wood from the braces when tap tuning is to make a number of guitars (and each would need to be made to completion) and each one shaving more and more mass off the braces until you go too far...and then just edge it back a bit.  Trouble is, for most of us that would take most of us a lifetime and fortune...  And then your offspring could maybe try the same thing with a different bracing pattern 

 

I believe you can apply engineering principles to hone in on the "right" set up for your individual bits of timber. Ie: test your timber for density, youngs modulus, etc then use maths to pump out ideal bracing sizes. Then use a frequency recording (oscilloscope?) to fine tune the braces. 

There's an aussie based, predominately acoustic, luthier forum that I read quite a bit and there's a commonly referenced book that they all pretty much use as the bible for this stuff. 

I've not read it myself, but it sounds like the books run you through every step of the process. I'm going to buy a copy very soon cause I'd love to have a go at an acoustic one day. 

Sounds like a nice shortcut around spending a few life times building. 

[Nicco]

Btw, fantastic looking guitar, Ash.

[Prostheta]

I'm certain we're not breaking any sort of new ground here, and there will be many people who have already spent lifetimes on this very same subject....which being thankful to them means we haven't done (or need to do) so yet  

The constraint or unknown in this mill of factors is always going to be the wood; you can determine ideal values for certain characteristics but you only have the choice of woods (or alternative materials, composites, modified materials, etc.) that are real. It may well be that one factor within all of this undermines the potential usage of a range or all others. The one that springs to mind might be dissimilar materials have differing movement ratios in response to humidity.

If or when I ever build an acoustic, I have 100% certainty that I will be relying on an existing body of experience to guide my arm to lay the first arrow into the target. I doubt that I could go my own route without first having a feel for the "established norm"!

This all being said, "Mahoganies" tend to be on the softer end of the scale than most hardwoods anyway. At least, true Mahoganies within the genus Swietenia. Alternative "African Mahoganies" (all still within the higher family Meliaceae) have more variability in terms of weight and elasticity. Sapele is the heavyweight of the lot, and I do like the airy lightness of Khaya Ivorensis/Senegalensis. I digress into wood nerdoidness....

[ADFinlayson]

12 hours ago, Nicco said:

Btw, fantastic looking guitar, Ash.

Thanks Nicco

12 hours ago, Prostheta said:

I'm certain we're not breaking any sort of new ground here, and there will be many people who have already spent lifetimes on this very same subject....which being thankful to them means we haven't done (or need to do) so yet  

The constraint or unknown in this mill of factors is always going to be the wood; you can determine ideal values for certain characteristics but you only have the choice of woods (or alternative materials, composites, modified materials, etc.) that are real. It may well be that one factor within all of this undermines the potential usage of a range or all others. The one that springs to mind might be dissimilar materials have differing movement ratios in response to humidity.

If or when I ever build an acoustic, I have 100% certainty that I will be relying on an existing body of experience to guide my arm to lay the first arrow into the target. I doubt that I could go my own route without first having a feel for the "established norm"!

This all being said, "Mahoganies" tend to be on the softer end of the scale than most hardwoods anyway. At least, true Mahoganies within the genus Swietenia. Alternative "African Mahoganies" (all still within the higher family Meliaceae) have more variability in terms of weight and elasticity. Sapele is the heavyweight of the lot, and I do like the airy lightness of Khaya Ivorensis/Senegalensis. I digress into wood nerdoidness....

I actually can't remember if I used legit or african mahogany for the braces, it might have been a mix of both that I got out of the offcuts bin. At any rate, all the african mahogany I have used has been quite soft and I've found the difference between the two to be negligible in terms of hardness, and workability. The only difference I've ever notices is that the Honduras stuff tends to look a little more on the pink side and african more yellow/orange.

[ADFinlayson]

I have been continuing on down the rabbit hole with the moderate success of #1.

I wrote #2422 for the serial on this one but it occurred to me after I closed the box that this is #25, that might cause some confusion for a luthier one day. So spruce braces this time and sticking with the thin ebony bridge plate. 

I forgot to take a photo but I drew around the inside of the solid brace of the arm contour on the underside then used that as a reference to  sand in the shape of the soundboard before sticking it on

 

Had to do a thorough job cleaning up the squeeze out here so I could glue some binding around the edge of the arm bevel.

I glued both the top and the back on this time while it was still in the form to try and help mitigate the deformity of the last one. although this one actually seems to hold it's shape outside the mould unlike no1.

Then I did the end graft out a of a piece of walnut. I chose walnut for my binding etc as it's much easier to bend than ebony, and still quite dark so hoping it would look good against the limba under finish and allow me to hide any woes.

Then I routed the binding channel in the top

This mean my smooth shape was no long smooth where it met the rebate so I tidied those up with a chisel and a sanding stick to get a nice transition again

once I did that, I glued in my sacrificial inner binding piece and rerouted that area of the channel 

Then I got to work on the actual binding, I cut it down on the sander between the two transitions so that it would bend around the extremely awkward curve.

The I carved the arm contour, the idea is that both of these pieces of binding are carved away with the bevel and are hidden by the veneer.

I left the veneer and the bevel with titebond on them for 1 hour as per the Driftwood Guitars tutorial then ironed the veneer on.

I sanded the walnut veneer down to .8mm which I now realise was two thick

It looks great but alas I managed to get some very visible glue lines in places and there is a small patch where I sanded through.

I then realised that there is a slight hump in the transition as it goes back up towards the strap button which meant that my carve isn't completely even and that was causing the glue line and the sand through - the veneer doesn't finish exactly where the spruce starts 

So I need to sand the veneer off, tweak the carve and do it again.

[Andyjr1515]

Looking very good indeed!

[ADFinlayson]

So I'm out of walnut which is annoying, I'm waiting for a delivery from Maderas and thought, seeing as the mould is empty and the side bender is still out... why not? 

I've got some african mahogany backs and sides sets that were dirt cheap, something like £5/pair of sides, same for backs and I have plenty of the same for making neck, and the end blocks etc So I thought I'd try another one as I am still yet to actually bend a set of sides with my DIY Fox bender. 

And they came out absolutely flawless - no waviness, flat spots or tears and fitted the mould perfectly. Woohoo.

I followed the advice of @Dave Higham and made a small modification to the bending machine, the hooks made a huge difference when it came to taking the sides out.

I don't have any kerfed linings so I thought I'd try doing solid linings. I thicknessed another side down to 2.2mm, cut it down into 18mm strips, taped them together and bent them. I dry fitted them with pegs and marked down where they need to be cut to get them to fit in with the end blocks.

Obviously 2.2mm linings is not enough of a glue surface so I planned to add another layer but first I thought I would interlock the side braces. I cut some quarter inch strips out of the leftover side and notched the linings so the braces with go all the way through.

Then I glued in the next layer of linings

so all in I have 6.6mm of glueing surface which is a hair under what the kerfed linings I was using would give me but I am already convinced that this is far superior. It's very difficult to get it in and out of the mould but that is because the shape is almost identical and there is absolutely no flex, I think it will break before it bends.

Here's the back glued up.

My thinking is to keep this one dead simple, magohany top and back, spruce bracing, no bevels, and I think tortoise shell binding and rosette would look cool. I've got some Aged Olympic white lacquer for a tele build I'm working on so it might look cool with a TV white style finish with dark grain if I can manage to do a tidy job of taping/scraping the binding/rosette.

 

[Bizman62]

Holy hole on the guitar top! You're having a construction line there, a factory even! And I very much appreciate you using the dirt cheap wood - in my experience they're still very good quality.

10 hours ago, ADFinlayson said:

I don't have any kerfed linings so I thought I'd try doing solid linings.

Nothing against solid linings, but knowing you have a bandsaw I wonder why you didn't make some? All it takes is a simple jig to prevent from cutting through and for cutting even sized blocks.

For those who don't figure out such a jig, it's simply a strip of wood behind the saw blade, fastened with clamps or double sided tape. If the saw blade is wide, a slot for the blade can be used for adjusting the depth. And for distancing a pin or piece of metal. Meh, let me draw it:

[ADFinlayson]

I've been back down the rabbit hole over the last couple of days after nearly 6 months of procrastination. Largely due to getting this route right. I'm not sure how the holes I drilled in the end block ended up off centre because the route was in the right place. 

and the alignment was pretty close when I did a test fit, just needed a little bit of fettling

I got some ears glued on and the fretboard in the right location with some locator pins

annoyingly, I managed to thickness the back way too thin - it was <1.5mm at the end in some places, so I ended up getting another back, thinning it down to 1.5mm and glueing it on to the back to make a ply which was a bit of an arse of a job and a shame because I really liked the figure of the original back.

With that issue fixed, I did the binding channel and got the binding on. I used the stewmac binding dremel attachment this time which I am still getting to grips with - it does cut parallel with the sides but it is quite hard to control so I had a couple of wobbles and ended up with a couple of gaps to fill and a few spots where the binding is slightly thinner after trimming, I think a lot of that is largely my fault for not thoroughly checking the consistency of the channel before glueing the binding in and I haven't got the will to route it off and do it all again.

This is what it's looking like all together and with the new back. I still need to sand all the scratches out of the neck and find sand the top/sides before I can think about doing anything finishing. Ideally I need to redo that bevel veneer but I'm tempted to just spray a bit of shader over it to make the glue line. I'm putting this one down as another learner anyway because it's got that flat spot at the top.

Something I like about the mortice/tenon joint as apposed to the butt joint I did on #1 is that I could make the heel considerable smaller without having to worry about revealing a threaded insert.

and a close up of the very simple inlay and neck heel.

 

 

[mattharris75]

Looking great!

What's the radius on your radius dishes for your top and back? Been planning an acoustic guild and am doing some data gathering...

[mistermikev]

lovely stuff as always brother.  love that backside... limba I s'pose.  really sharp.

[ADFinlayson]

50 minutes ago, mattharris75 said:

Looking great!

What's the radius on your radius dishes for your top and back? Been planning an acoustic guild and am doing some data gathering...

Thanks, I've got a 15' dish for the back and 28' for the front. I stuck them to each other so I just flip them over when I want to change radius, also works as a good clamping caul when gluing the top/back on

[ADFinlayson]

34 minutes ago, mistermikev said:

lovely stuff as always brother.  love that backside... limba I s'pose.  really sharp.

thanks mate, yeah as acoustic woods go, limba is pretty cheap, easy to bend and looks a bit more interesting than other options. I got myself another set recently so I think I'll do another limba build at some point 

[Bizman62]

Looks very nice and I guess the build quality is at least on the same level with many factory built ones.

7 hours ago, ADFinlayson said:

I used the stewmac binding dremel attachment this time which I am still getting to grips with - it does cut parallel with the sides but it is quite hard to control

You might be interested in the modification Jerry Rosa has made to that tool: